Ahubbard

I appreciate all the help guys. We will get this fixed!!! I would love to get any info people have on a fix to this resonant ride problem... makes it easier when I talk to pump shop if I have an understanding about things. Sent from my iPhone using Tapatalk

My problem definitely isnt under load. It actually does it most prominently when I rev the motor up past 1200 and then let it back to 1200. Or for example when I come to a 35 mile per hour zone and don’t downshift if my foot is lightly pushing the pedal as i coast through it starts the gallop. Is there potential for this condition to damage anything if I run it? I am hoping to get through my busiest season and get to October/November before I take the pump off and send it to the shop. Sent from my iPhone using Tapatalk

Yes I will get that feeling when I drive. Almost feels like the spring is too light on the throttle return even though it’s not. I will let my foot of the throttle some and lay back in to correct that sometimes. When this does it at 1200 it almost is like a horse galloping. Rhythmic and kinda shakes the motor. Sent from my iPhone using Tapatalk

Like governor fluctuating at this rpm? Sent from my iPhone using Tapatalk

I am not sure what this means Sent from my iPhone using Tapatalk

Ok... here we go. I took a trip to Antrim Diesel today. Kevin checked my injectors and didn’t find one good one. Lol. MAYBE number 6 was decent but still bad. #1 and #2 were terrible. Think just streaming fuel on the pop tester. Yikes. Guess I got my use out of those. Traded them in for a reman set he had on the shelf that have a little better flow. Came home this afternoon and installed them. That solved my return fuel problem. Nice clear fuel with no bubbles in the return line. Took that running out of fuel sound away. But I still have the shake/chug at 1200 rpm. That’s a little frustrating. Can’t figure out why it is at only one specific rpm. Smooth as silk at idle. And smooth above that..even at 1250 for example. Wonder if this could be in the pump. Someone else suggested a cracked line between the pump and injector somewhere. I didn’t have them totally out I just backed the nuts out and pulled then back an inch to clear the injectors when I switched them. I should have picked kevins brain a little more about it at Antrim. But with a 4 hour ride one way I guess I got a little hurried to get home and install my new toys. I wish I could post a video here so you could hear it. On the bright side the new injectors are great! Test drive shows a noticeable power gain and I feel like (other than 1200 rpm) the engine has less vibration. Took my turbo boost pressure from about 28 psi to 35. Gotta watch the pyro harder now!!! Probably will have to get a bigger turbo... might as well have the pump worked over while they check it..... lol ANY MORE IDEAS?! I am going to work the truck tomorrow. Gonna have to keep running it. I am just not sure where to go from here. Sent from my iPhone using Tapatalk

I think I am pretty set that I have a problem there and I should pull injectors and see what’s up. They do have 25,000 hours on them. I just didn’t want to jump to conclusions and not diagnose. I feel like if taking that return line off the head eliminates the air cycling around my injection pump then I probably have narrowed it down to injectors. Too bad...I should have planned ahead. Last winter would have been a good time to do injectors. Dump truck suppose to be running in summer!!!! Thanks for the help I will keep you posted what I find. I figured I had a lot of information but I didn’t know exactly how to use it. Guys in here always seem to know their stuff!! Sent from my iPhone using Tapatalk

Just now I pulled the return line off my head. I put my thumb over the line to keep fuel from feeding back from the pump. It cleared up the air in that lower line. I am getting no fuel out of the front head. There is pressure there when I put my thumb over but no fuel. I took the little crossover to tube off from between the heads. Ran truck with it off. Back head consistently spills fuel out and front head has nothing. Unless I put my thumb over it then I get a big shot of air and a small surge of fuel when I let my thumb off. Is it possible to have a bad injector or cup that is letting compression in the system causing my air problem in the return lines and pump? Sent from my iPhone using Tapatalk

After further inspection that 2 prong banjo fitting just has a small orifice behind it. Nothing seemed blocked there. I looked harder at the return line from the head and am not really getting any fuel coming back through that line. Just the first couple inches have fuel in it. But that lower line flows a ton of air through it. I ran the suction line into a pail of diesel and then also ran it with the outlet line from the lift pump direct to the injection pump. No change either way. Is my lift pump or flowing enough or should I be thinking something with the injection pump? Sent from my iPhone using Tapatalk

Oh man I meant Kink the return line not link it. Damn autocorrect lol This line has air What is this ? Sent from my iPhone using Tapatalk

Hey guys, I have a 1994 EM7-300 PLN fully mechanical motor in my truck. I am having a problem with the fuel. It is not as noticeable when the truck is cold in the mornings but after I work the truck for a while it gets pretty distinct. It will do it when it is cold but sort of clears up quickly, when warmed up I can set the throttle lock at 1200 and it keeps doing it continuously. The engine shakes/misfires around 1200 rpm. It sort of sounds like it is running out of fuel. Smooth at idle, runs good above that rpm. I put a gauge on the supply line going into the injector pump and have about 20psi at all rpm. Not sure what I should have there. After work Friday I set the throttle lock to 1200 and cracked open injector lines. They all chugged the motor good but #1 not as much. I swapped #1 and #3 injectors and that did not change. Cracking #1 still sounded like less of a chug. I started to think that maybe because #1 is farthest away from fuel supply that it wasn’t getting enough fuel. While checking things over again I see air bubbles in the return line. I have a clearish plastic/rubber hose on there and I can see through. Actually there doesnt seem to be air in the return from the head to the back side of the pump. But there is air in the short line form the back side of the pump to the front where the return check valve is. If I link that line off while the truck is running at 1200 it seems noticeably smooth up. Is that because I am cutting off those air bubbles or does linking that off raise the pressure and help keep it from running out of fuel? Anyway I am going to put new return lines on today and make sure that they are good and tight on the fittings. Also, I see that the return fitting on my side of the pump is a check valve with a spring in it. What is on the back side in by the engine where those 2 return lines meet? It is like a Y fitting where the return line comes from the head then a short line comes around to the front. Is there some sort of check valve in that too? Any knowledge of what I am looking at would be great!! Also any ideas of thinks I am not thinking to look at. I want to start with bigmacktrucks first! Any shops around I think will throw in injectors then if that’s not it try a new injection pump. I don’t have the $$ to be just guessing at big parts and downtime. I want to get it diagnosed first. Thanks Guys!! Sent from my iPhone using Tapatalk

This is cool! Do you have a picture of the interior? Sent from my iPhone using Tapatalk

Wow this truck looks amazing!! Awesome job. I would love to see more pics too! Sent from my iPhone using Tapatalk

My dump before I changed the motor was approximately 18000 hours and 340,000 miles. It's a 99. Sent from my iPhone using Tapatalk

I don't have any diagrams but I can measure my e7 or take pictures for you. Sent from my iPhone using Tapatalk

Oh yeah I am happy! She runs good, hard pull the pyro hung at about 900 and I saw about 34psi boost. WAY more low end than the etech. I am sure I am gonna like this motor. Also the dynamat did quiet things some. It's not as quiet as a Cadillac but I can hear a difference. Sent from my iPhone using Tapatalk

Neat lookin rig! Sent from my iPhone using Tapatalk

Ok thanks. I will have to get used to eyeing the pyrometer again. That never was a concern in the etech. I will give a report tomorrow. I got a load of sand headed to a farmer. There is a pretty good hill in between my place and his. Kinda feel like a kid on Christmas Eve. I might be too excited to sleep. Sent from my iPhone using Tapatalk

Ok theakerstwo I will remember that. I wonder how much boost pressure is too much for my set up? I don't want to over do it for sure. Sent from my iPhone using Tapatalk

I also put dynamat on the floor and firewall and added some padding to help quiet the interior. There are a few more things I want to spruce up on the old girl but I am out of money. I need some warm stone hauling weather. Lol Sent from my iPhone using Tapatalk

Sorry my pictures are about all from the same angle. I finally got the hood back and things are wrapped up. I think it came out well. The donor truck throttle linkage was a little different than I needed and I decided to build my own. But before I started I called my Mack dealer. I had a serial number from an rd with mechanical already. It fit my budget to get new parts right from Mack. Pedal to pump. Made that part easy. As far as power goes, I put my s300 turbo off the etech on her. Also I slid the fuel plate ahead and spun the aneroid star wheel a few clicks until I got a nice puff of black out the stack that clears right up when I crack the throttle good. I got to test drive today and m seeing boost pressure as much as 30 psi when I get on her. I will be hauling a load tomorrow so I will be hoping for some nice power. Thanks for checking out my post guys. I have had a lot of fun with this project Sent from my iPhone using Tapatalk

This looks like a cool idea. Be sure to keep us updated with pictures. I would love to keep track of the progress on this. What's the motor and tranny? Sent from my iPhone using Tapatalk

Very nice! Sent from my iPhone using Tapatalk

Thanks for all the replies guys. Things looking good. Just waiting on my hood to come back. I had a guy fixing some fiberglass and painting. I can't wait to test drive! Goodbye ECM! Goodbye mess of wires! Sent from my iPhone using Tapatalk

I am partial to new style RD (sorry hatcity!). I also have always liked the looks of superliners Sent from my iPhone using Tapatalk